Apparatus for extracting precious metals from ores



Patented Jan. 10', I899.

L. E. PORTER. APPARATUS FOR EXTRACTING PRECIOUS METALS FROM OBES.

A lication filed Aug. 18, 1896.)

(No Model.)

UNITED STATES PATENT OFFICE.

LEWIS E. PORTER, OE LOS ANGELES, CALIFORNIA, ASSIGNOR TO THE POR- TERGOLD AND SILVER EXTRACTION COMPANY, OF CALIFORNIA.

APPARATUS FOR EXTRACTING PRECIOUS METALS FROM ORES.

SPECIFICATION forming part of Letters Patent No. 617,512, dated January10, 1899.

Application filed August 18, 1896. Serial No. 603,129. (No model) ToctZZ whom it may concern: I

Be it known that I, LEWIS E. PORTER, a citi- 'zen of the United States,residing at Los Angeles, in the county of Los Angeles and State ofCalifornia, have invented new and useful Improvements in Apparatus forExtracting Precious Metals from Ores, of which the following is aspecification.

My invention relates particularly to those apparatus in which theprecious metals are dissolved from ores by means of chemical solotionsand electrical action.

One especial object of my invention is to provide means whereby the pulpmay be electrically treated while undergoing chemical action withoutpolarizing the electrodes.

Another object of my invention is to provide means for preventing theescape of the gases produced during the process of treatment and to soconduct thetreatment that such gases will produce a pressure and byagitation will be brought into intimate contact and admixture with everyparticle of the ore being treated, the generation of such gases and theliberation of the precious metals from the ore being produced andassisted by the passage of a current of electricity through the pulpduring the chemical treatment.

Another object of my invention is to provide improved means whereby theagitator serves as a filter for extracting from the slimes practicallyallof the precious -metal solutions after the chemical action hasbeencompleted.

. parts hereinafter fully set forth and claimed.

The accompanying drawings illustrate means whereby my invention may bepracticed.

Figure 1 is a vertical longitudinal mid-sec tion of my improved combinedagitator and filter. Fig. 2 is a plan view of a plant Whereby myinvention may be practiced. Fig. 3 is an enlarged fragmental section ofthe casing and filter.

ployed in practice are of sheet metal, and I have found it advisable tocover them with canvas 0 or other porous fibrous material in order toprevent the metal deposited thereupon from being scoured ofi by theaction of the pulp during agitation. The anodes are preferablyinsoluble, and in practice I have used carbon anodes with great success.

Into one end of the bore a of the shaft I drive a metal plug D, andbetween the plug and the shaft I arrange a collar of insulating material61, so that the plug is insulated from the shaft. Secured to the end ofthe plug is an electrical conductor E, which is insulated and leads fromthence partially through the bore of the shaft. WVires f lead outthrough openings a"through the shaft and are electrically connected withthe cathodes, so that by means of the commutator-brush d electri calconnection is made with the dynamo D nected with the shaft A, when thecommutator-brush cl" rests upon the shaft and the dynamo D is operatedthe anodes are electrized. Secured upon this shaft A and surrounding theanodes andcathodes I provide a combined agitator-barrel and filter G.This consists of an outer imperforate casing G, made of any suitablemetal or material, and a lining II, of suitable filtering material,introduced inside of the casing and arranged to leave a space H betweenthe filter and the barrel, through which the filtered liquid may flow tothe outlets J J. In practice I find it convenient and effective tointroduce first a screen h, made of coarse wire, preferably one- Theanodes 0 being electrically coni be so effective in practical operation.

fourth of an inch in diameter. Upon this screen I introduce a secondscreen 7L,which is of finer mesh than the other. Upon this finer screenI place any suitable filtering material 7t--such as woolen blanket,burlap, or asbestos filtering-elothas maybe found suitable or desirable.Uponthis filtering material I place a fine-mesh screen h to hold thefiltering material in place, and upon the inside of this fine screen Iarrange another screen h", of coarse wire, to receive the wear of thematerial being agitated. I have found this to be practically the mostefficient and satisfactory manner in which the filtering-lining can bearranged within the barrel. It is absolutely essential that thefiltering-lining be supported a sufficient distance from the walls ofthe barrel to allow the filtered liquor ready escape between the filterin g-linin g and the walls of the barrel to the discharge-openin g. Whenthe barrel with its contained load of pulp is revolved at a high rate ofspeed, an enormous pressure is thus brought to bear against thefiltering-lining, and were it not firmly supported it would be forced sotightly against the walls of the barrel as to prevent the escape of anyliquor whatever through the filter. The same end might be secured byroughening the inner face of the barrel; but this would be moreexpensive, and I do not believe would The electrodes, especially theanodes, are attached to the shaft so that they revolve with the barrel,and while the pulp is being agitated the barrel is being revolved at aslow rate of speed, the pulp not revolving with the same speed as thebarrel, and therefore the pulp scours against the electrodes, keepingthem from polarizing.

At each end of the barrel an iron ring I is arranged to clamp the screenand the filtering material tightly against the wall of the barrel, so asto prevent any of the pulp from gaining access to the space H betweenthe barrel and the filtering material without first passing through thefilter. Near the midlength of the drum I provide an opening g, which isclosed by means of a removable plug g, which is similar to an ordinaryhand-hole plug for boilers, but is convex upon its inner face, so thatwhen the pulp is being filtered the liquid will readily flow off of theplug to the filter. A ring H is arranged surrounding the opening throughthe screens, and in order to preventthe unfiltered pulp from flowingfrom such opening into the space H the ring is tightly bolted to thewalls of the casing in order to firmly clamp the filtering material tothe casing. I provide two discharge-openings J and J, which open throughthe walls of the easing into the space H between the filtering materialand the walls of the barrelthat is to say, the coarse screen h holds thefiltering material a sufficient distance away from the walls of thebarrel to leave enough space to allow the liquid to flow readily fromall portions of the barrel toward the dis charge-openings. Thesedischarge-openings J J are closed by means of removable plugs A suitablehousing 0 is arranged to receive the liquor discharged from the openingsJ J and to conduct it to a suitable receptacle (not shown) arranged toreceive it.

K represents the line-shaft, upon which are mounted two driving-pulleys7.; and It. The larger pulley 7c is of a diameter equal to the diameterof the barrel G. Upon the shaft A I secure a driven pulley A, which isof. the same diameter as the pulley it. Thus when the drum is to berotated slowly the belt L is arranged upon the pulley 7t and the drum G,as indicated in dotted lines in Fig. 2, and when greater speed isrequired the belt is shifted to the pulleys A and 7.1. At the end of theshaft opposite the plug D, I arrange a water and steam tight packing M,so that by means of the water and steam pipes m m Water or steam may besupplied to the bore a of the shaft and discharged into the barrelthrough openings at".

In practical operation the pulp or material to be treated is saturatedwith a suitable solution and placed in the barrel by removing the plug 9and introducing the material through the opening g.

The chemical solution which I employ in treating all ordinary oresconsists of about the following proportions: water; common salt, enoughto give suitable conductivity, ordinarily from one-quarter to three percent. 5 eyanid of potassium, one-quarter of one per cent., and causticsoda, enough to neutralize the acid salts in the ore. treat about threetons of ore. After the chemically-saturated ore is introduced into thebarrel the plug is replaced, care being taken that the plugs jj aretightly screwed hom e. Then the belt L is arranged upon the barrel, andthe small driving-pulley 7c and the line-shaft are rotated by anysuitable power to cause the drum or barrel to slowly rotate, thus toagitate the pulp. The dynamo D is set in operation, and the electricalcurrent generated passes to the shaft A through the medium of thecommutator-brush d, and the anodes O are thus electrized. Theelectricity passes from the anodes through the intervening pulp to thecathodes C, and as the chemical action proceeds a percentage of theprecious metals is deposited upon the cathodes, and the electricalcurrent returns through the electrical connection of the plugD and thecom mutatorbrush d to the dynamo D, thus completing the circuit. Byreason of the anodes being constantly subjected to the scouring actionof the pulp undergoing agitation the bubbles of oxygen gas which formthereupon are scoured off and rise into the top of the barrel, which isnot entirely filled with pulp. The chlorin gas generated by theelectrical act-ion also rises to the top of the barrel, and in a shorttime considerable pressure is generated, sometimes reaching thirty orforty pounds to the square inch. As the agitation continues these gasesOne ton of the solution will are reabsorbed by the water, and everypor-- tion and particle of the ore is subjected to their action. Sinceno gases can escape from the barrel, the operation is economicallyconducted and is more rapid than is possible by any other means. Apercentage of the metal is deposited upon the cathodes O, and as fast asit is deposited the cyanogen is released and the solution regeneratedthereby.

By employing the salt I make of the solution a good conductor forelectricity, enabling me to use a current of low voltage and to producea large quantity-of oxygen and chlorin which is liberated at the anodes,and were it not scoured off by the pulp would assume the form of gaseousbubbles upon the anodes and cause partial or total polarization thereof.This has heretofore been the principal difii- .culty to be overcome intreating ores electrically and chemically. The salt when decomposed bythe electrical current forms chlorin gas which, in combination with theoxygen gas and the cyanid, forms a very powerful solvent. The causticsoda is very cheap and neutralizes the acid salts in the ores, leavingthe metals free to be acted upon by the oxygen and chlorin gases and thecyanogen. There are chemicals other than caustic soda which willneutralize the acid salts; but they are, so far as I am aware, either soexpensive as to be incapable of use in the treatment of low-grade oresor do not perform the service required in as efficient a manner as doesthe caustic soda. lVhen the electrical current is passed through thechemically-saturated pulp, not only is oxygen and chlorin gas liberated,as before explained, but the oyanid is converted into cyanogen, one ofthe most powerful solvents known, and this cyanogen immediatelydissolves as much metal as it will combine with, passes to the cathodes,where the metal deposits, liberating the cyanogen,which again mixes withthe pulp, dissolvesmore metal and deposits it, and again regeneratingthe solution until all the metal is dissolved and deposited. The chlorinand oxygen gases confined under heavy pressure produce a condition mostfavorable for the dissolution and deposition of the metals by thecyanogen, and the expense and time necessary for the treatment of theore are reduced to a minimum, thus enabling me to treat at a profit oreswhich cannot be successfully treated by any other known process.

I am aware that it has been proposed heretofore to use sodium chloridand potassium cyanid in conjunction with an electrical current. Theeffect of this is that when the chemicals are mixed with the pulp if theore contains acid salts these salts attack the cyanid, converting itinto hydrocyanic acid. When the electric current is afterward passedthrough the ore, caustic soda is produced; but the cyanid which has notbeen attacked by the acid salts is attacked by the hydrochloric acid andrendered inert and valueless for dissolving the metal. By this process avery large amount of cyanid is necessary to dissolve a very small amountof metal, while with my invention the acid salts are neutralized beforethe electric current is passed through the chemically-sat'urated pulp,and the hydrochloric acid as fast as liberated is neutralized by thepresence of the caustic soda present in the solution.

When the metals are dissolved, the rotation of the barrel is stopped andthe belt is shifted from the barrel to the smaller driven wheel.

A and the larger driving-wheel 7s upon the line-shaft K. The plugs j jare removed, thus to leave the openings J J unobstructed, and theline-shaft is revolved to cause the barrel to rotate at a high rate ofspeed. The centrifugal action causes the pulp to spread itself about theinterior of the drum and also causes the precious liquors tov bedrivenout through the filter and into the intervening space H betweenthe filter and the casing G, from whence it escapes through the openingsJ' J and is caught by the housings O and conducted to the trough O,which leads it to a suitable receptacle. (Not shown.) By revolving abarrel of four feet in diameter at a speed of seven hundred revolutionsper minute practically every particle of liquor can be extracted fromthe slimes, no matter how talcy or clayey they may be. When the supplyof liquor originally supplied to the pulp becomes exhausted, then wateris turned on through the bore a of the shaft and the remaining liquor inthe pulp is't-horoughly washed therefrom. "When the extraction iscompleted, the plugs j j may be replaced,water introduced into thebarrel to form the pulp into slush, the plug 9' removed from the openingg and the pulp discharged from the barrel, a new-charge introduced, andthe operation is repeated.

Now, having described my invention,what I claim as new, and desire tosecure by Letters Patent, is

1. The combination set forth of a casing provided withdischarge-openings for filtered liquid and closed by removable closures;a lining of filtering material within the casing, having a space betweenit and the casing; means for introducing pulp into and removing it fromthe filter-lined chamber; a housing surrounding the cylinder andarranged to catch the filtered liquor discharged from the openings whenthe casing is revolved; and means for rotating the casing at a high rateof speed.

2. The combination set forth of a rotatable barrel; a lining offiltering material arranged in the barrel and to leave a space betweensuch lining and the walls of the barrel; an

catch the filtered liquor discharged through the opening when the casingis rotated; and means for rotating the barrel at a high rate of speed.

3. In combination, a shaft with a longitudinal bore; a barrel mountedupon such shaft; a cathode and an anode plate arranged upon such shaftand insulated from each other; an electrical conductor passing throughthe bore of the shaft and connected with one of the plates; means forsupplying electricity to the other plate; means for introducing materialto be treated into and removing it from the barrel; and means forrotating the barrel.

4. In combination, a shaft provided with a longitudinal bore and havingone end closed by means of a plug insulated from the shaft; a source ofelectricity connected with the plug; a series of anodes mounted upon theshaft and insulated therefrom; an electrical connection between the plugand each of the anodes; a series of cathodes mounted upon andelectrically connected with the shaft; suitable means for supplyingelectricity to the shaft and the cathodes; a barrel arranged upon theshaft and inclosing the anodes and cathodes; a lining of filteringmaterial arranged inside the barrel; an opening for introducing insideof the filtering'lining the material to be treated; dischargeopeningsarranged to allow the discharge from the barrel of the liquid whichpasses through the filter; and means for rotating the barrel.

5. The combination set forth of ashaft provided with a longitudinalbore; a barrel arranged on the shaft; series of anode and cathode disksarranged upon the shaft, the anodes being insulated therefrom; aninsulated electrical connection passing through the bore of the shaftand arranged to electrize the anodes; a source of electrical energy;

means for supplying electricity to the shaft and the cathodes; suitablemeans for introducing steam or water into the bore, such bore beingprovided with passages opening through the shaft into the barrel; alining of filtering material arranged inside the barrel with a spacebetween it and the walls of the barrel; an opening arranged to allow thematerial to be treated to be introduced into and removed from thebarrel; openings arranged to allow the filtered liquid to escape fromthe barrel; and means for rotating the barrel.

6. An appliance for saving precious metals com prising a rotatablebarrel having arranged therein and resting against the wall of thebarrel, a lining of filtering material, and provided in such wall withan outlet for filtered liquor; a removable closure for the outlet;cathode and anode plates arranged in the barrel and adapted to pass acurrent of electricity through the material in the barrel; and a housingsurrounding the barrel to catch the filtered liquor discharged from theoutlet when the barrel is rotated at a high rate of speed.

'7. In an appliance for saving preciousmetals, the combination set forthof a rotatable casing provided with a discharge-opening; a removableclosure for such opening; a lining of coarse wire-netting arrangedinside the cylinder; a lining of fine Wire-nettin g arranged inside thefirst lining; alayer of filtering material arranged inside the finenetting; a fine wire-netting arranged inside the filtering mate rial; alining of coarse Wire-nettin g arranged inside the fine netting; andmeans for rotating the barrel at a high rate of speed.

L. E. PORTER.

Vitnesses:

ALFRED I. TowNsENn, JAMEs R. TOWNSEND.

